AFA4000/E VAV Airflow Controller / p.45
4.3.5 Sash Low switch
When a Tiptronic control is not in use, a Sash Low switch is used to signal to the Auto Sash
Control Unit that the fume hood sash is closed.
The switch can be either a mechanical roller lever type micro-switch or an inductive proximity
switch.
Figure 10: Typical Sash Low switches
4.3.6 Sash Position sensor
The Sash Position Sensor comprises of a flexible cable, a spring-loaded spool and a
potentiometer. It is used, in conjunction with the Tiptronic control option, to detect and
measure vertical sash movement and the position of the fume hood sash.
During the initial on-screen calibration set up the sash controller detects the sensor direction of
travel and then provides position information of the sash to the Auto Sash Control Unit, to
enable calibration of the sash open / closed positions.
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